Method of treating silk



Patented Apr. 17, 192s.

UNITED STATES PATENT OFFICE.

,gkMES C. MACKEY, OI PATERSON, NEW JERSEY, AND JOSEPH S. KAUFMAN, OF NEW YORK, N. Y., ASSIGNORS OF ONEeTHIRD TO VAN RENSSELAER LANSINGH, OF PEL- HAM, NEW YORK.

METHOD OF TREATING SILK.

No Drawing.

The present invention relates to methods of treating silk, and is more particularly directed toward an improved method of wei hting silks in the piece or skein.

T 'e ordinary process of weighting silk has involved the formation of tin phosphate in the fibres and then treating this with sodium silicate. Sodium aluminate, aluminum sulphate and lead acetate have also been used, but the sodium silicate process has been more general. It, however, has not been entirely satisfactory for it may tender the goods considerably and leaves them in a rather harsh condition. It is also likely to result in white marks appearing in the goods when acid colors are used. Silk treated with sodium aluminate, aluminum sulphate, and lead acetate cannot be dyed satisfactorily wit-h acid colors as the bath affects the 'weighting. It is therefore, diflicult to obtain exact results in color and weighting when using this weighting material. These peculiarities apply particularly to the weighting of silk in piece goods, though likewise true in skein silk in more moderate degree.

According to the present invention, the process involves the use of sodium tungstate instead of the use of t-he.compounds referred to above, and the silk becomes weighted with what is probably tin phospho-tungstate. Silk treated according to the present process is not tendered, and is found to be remarkably soft and uniform. The process is adapted for use in the skein or in the piege, and the silk may be dyed with either acid or direct colors with excellent results.

The present method of treating silk may conveniently be carried out in the followin manner: After the silk has been degummed and Washed in any of the well known manners, it is immersed in a cold bath of weak muriatic acid about 5% by volume. After extracting, the goods are put into a cold bath of tin tetrachloride solution of about 20 to 30 Baum and left in this bath for about an hour. After "a thorough washing the goods are given a treatment in a solution of sodium phosphate of about 8 Baum, at a temperature of from 120 F. to 130 F. (The lower temperature being preferable.) The sodium phosphate counteracts the acid in the tin tetrachloride and results in the formation of tin phosphate in the silk. The goods are again extracted and thoroughly Application filed August 19, 1925. Serial No. 51,088.

washed and put into a second tin tetrachloride bath of about 19 to 20 Baum, cold. This pass inthe tin is given to provide a linking agent for the sodium tungstate.

After the second treatment with tin, it is necessary to thoroughly wash the goods, care being taken to clear the silk from all traces of acid and from all loose tin. The silk is then immersed in a sodium tungstate bath of 25 Baum at about 120 to 130 F. for about an hour. The sodium tungstate reacting with the Weighting material previously applied to the silk, has functioned as a fixing agent to provide neutral base weighted silk. This brings about the formation of tin phosphotungstate in the fabric. The goods are again extracted and thoroughly washed.

The goods are then ready for dyeing, printing or otherwise processing them. The silk is in a condition in which an absolutely neutral base is provided for the dyeing process in the same manner as though on unweighted or pure silk. Acid dyes may be used without affecting the weighting. I'ncreased weight resultant from such treatment is approximately 25% over raw weight. If more weighting is desired, further passes in tin and phosphate are given before the final immersion in sodium tungstate.

We claim: I

-1. Weighted silk which has tin phosphotungstate in the fibers to weight the same, said weighted silk being a neutral base havmg the same properties as regards dyeing and printingas exist in unwei hted silk.

2. The process of treating silk which comprises successively immersing it in solutions of tin tetrachloride, sodium phosphate, tin tetrachloride, and sodium tungstate, the silk being thoroughly washed after each of the aforesaid immersions.

' The process of treating silk which comprlses successively immersing it in solutions of tin tetrachloride, sodium phosphate, tin tetrachloride,:and finally in sodium tungstate -of about 25 Baum and at about 120 to- 130 F., the silk being thoroughly washed after each of the aforesaid immersions. 4. The step in the weighting of silk which comprises the formation of tin phosphotungstate in the fibres, said weighting material being 1nert so far as affecting the dyemg and printing'properties of the silk.

5. The method of increasing the weight- State' of New Jersey, this 13th day of ing of silk, which consists in subjecting it August, 1925. I i

to alternate passes in tin tetrachloride and JAMES C. MACKEY. 10 sodium phosphate, and then to a solution of Signed in the city of New York, in the 5 warm sodium tung'state which follows the State of New York, this 1 2th day of August,

final pass in tin tetrachloride, 1925.

Signed in the city of Paterson, in the JOSEPH S. KAUFMAN, 

